1. Field of the Invention
This invention relates to a camera in which the entire photo-taking lens barrel is displaceable in the direction of the optic axis.
2. Related Background Art
Various cameras in which the entire photo-taking lens barrel is displaceable in the direction of the optic axis are known and recently, a two-focus camera has attracted attention. In this camera, a phototaking optical system is comprised of a main optical system and a sub optical system, and when the main optical system is moved forwardly, the sub lens is inserted onto the optic axis rearward of the main optical system, whereby the focal length can be changed. Such camera is known from patent publications such as Japanese Laid-Open Patent Applications No. 76919/1977, 33027/1979 and 202431/1983. However, in these publications, no mention is made of a shutter blade for controlling the exposure of a film. Japanese Laid-Open Patent Application No. 19926/1984 may be mentioned as a publication which proposes a shutter blade in a two-focus camera. In the two-focus camera provided with this shutter blade, a moving mechanism for focusing is provided around a main optical system. A shutter blade driving mechanism and a shutter blade serving also as a diaphragm are provided immediately rearwardly of the main optical system, and further, a sub optical system is inserted rearwardly of the shutter blade serving also as a diaphragm. Thus the structure of the shutter blade driving mechanism is very complicated and assembling work requires a long time and experience. Also, an outer shell surrounding the main optical system, the shutter blade and the shutter blade driving mechanism is formed into a square shell so as to also surround the lens frame of the sub optical system which is in a retracted position outside the optic axis. This has led to the creation of a useless space therein and moreover, there has been a disadvantage that the outside of the outer shell must be further covered with a square shell cover to make the space between the outer shell and the camera body light-tight. In the known cameras including the Japanese Laid-Open Patent Application No. 19926/1984, no consideration is given to a lens barrier blade for protecting the main optical system.